Liquid Crystal Display Device and Manufacturing Method Thereof

ABSTRACT

A liquid crystal display device includes a thin film transistor substrate having a pixel region and a frame region, and a color filter substrate. The frame region includes a first metal wire that surrounds the outside of the pixel region, and a second metal wire that is formed so as to surround the outside of the first metal wire. The first metal wire has at least one slit at an area overlapping with a seal material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/437,037, filed Apr. 2, 2012, the contents of which are incorporatedherein by reference.

The present application claims priority from Japanese application JP2011-087713 filed on Apr. 11, 2011, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display and amanufacturing method thereof.

2. Description of the Related Art

As display devices for information communication terminals such as acomputer or television receivers, liquid crystal display devices havebeen widely used. The liquid crystal display device is a device whichdisplays images by changing alignment of liquid crystal molecules sealedbetween two substrates of a liquid crystal panel and varying atransmissive extent of light applied to the liquid crystal panel from abacklight.

FIG. 12 is a partial cross-sectional view schematically illustrating astructure of a liquid crystal module 700 in the related art used for theliquid crystal display device.

The liquid crystal module 700 includes a liquid crystal panel 800 whichhas a display surface 810 and controls alignment of the liquid crystal,a light guide plate 710 to which light from a light source (not shown)is incident and allows the light to travel toward the display surface,an optical sheet 740 which applies the light emitted from the lightguide plate to a display region so as to be uniform and has a pluralityof sheets, and the like. In addition, the liquid crystal panel 800includes an upper polarizer 801 which transmits only light polarized inone direction therethrough, a lower polarizer 805 which transmits onlylight polarized in a direction perpendicular to the one directiontherethrough, a color filter substrate 802 which has color filters R(red), G (green) and B (blue) for the respective pixels, a TFT (ThinFilm Transistor) substrate 804 which is provided with circuits (notshown) generating an electric field for each pixel, liquid crystalcomposition 803 which is sealed between the color filter substrate 802and the TFT substrate 804, a black matrix 806 which is formed on thecolor filter substrate 802, and a seal 807 which is formed from a UV(ultra violet) curable material for sealing the liquid crystalcomposition 803 between the color filter substrate 802 and the TFTsubstrate 804.

In such a liquid crystal module, a black layer called the black matrix806 is provided such that the light applied from the backlight does notleak in a frame region which is located directly outside the pixelregion displaying images, and further the light is prevented fromleaking by extending the polarizers 801 and 805 disposed at the upperand lower parts of the liquid crystal panel toward the frame region soas to increase a light blocking property.

SUMMARY OF THE INVENTION

However, with a demand for thinned structures at present, the polarizersare designed in a small size in order to prevent interference with theframe or the like. Thereby, the light from the backlight which can bereduced in its intensity by the polarizers in the related art reachesthe black matrix without reduction in the intensity, and thus the frameregion blazes with blue or is brighter than the display region duringthe entire black display, whereby there is a concern that performance ofthe display device is influenced.

The present invention has been made in consideration of thesecircumstances, and an object thereof is to provide a liquid crystaldisplay device and a manufacturing method capable of increasing a lightblocking property in a frame portion.

According to an aspect of the present invention, there is provided aliquid crystal display device including liquid crystal composition thatvaries transmittance of light by changing in alignment; and a thin filmtransistor substrate that is provided with a circuit formed for each ofpixels and generating an electric field for controlling alignment of theliquid crystal composition, wherein the thin film transistor substrateincludes a pixel region that is a rectangular region in which the pixelsare formed plurally; and a frame region that is a region located outsidethe edge of the pixel region, and wherein the frame region includes alight blocking metal wire that surrounds the outside of at least threesides of the rectangular pixel region and has slits formed so as topartially transmit light therethrough.

In the liquid crystal display device according to the aspect of thepresent invention, the light blocking metal wire may be connected to aterminal of the circuit having a fixed potential.

In the liquid crystal display device according to the aspect of thepresent invention, the frame region may further include a disconnectiondetection metal wire that is formed so as to surround the outside of thethree sides and is used to detect disconnection, at the outside of thelight blocking metal wire.

In the liquid crystal display device according to the aspect of thepresent invention, the disconnection detection metal wire may beconnected to a terminal for connection to an external circuit.

In the liquid crystal display device according to the aspect of thepresent invention, the slits may be linearly formed in a wire directioninside the light blocking metal wire or may be formed in a checkeredpattern.

The liquid crystal display device according to the aspect of the presentinvention may further include a polarizer that transmits only lightpolarized in a specific direction therethrough, and the polarizer mayhave the same size as that of the pixel region.

In the liquid crystal display device according to the aspect of thepresent invention, the light blocking metal wire may be formed in thesame layer as a gate wire of the circuit.

According to another aspect of the present invention, there is provideda liquid crystal display device manufacturing method including a metalwire forming process of forming a light blocking metal wire whichsurrounds the outside of at least three sides of a rectangular pixelregion where a plurality of pixels are formed, and has slits forpartially transmitting light therethrough, on a thin film transistorsubstrate; an ultraviolet-ray irradiating process of curing a sealmaterial by irradiating the seal material for bonding the thin filmtransistor substrate and a color filter substrate to each other andsealing liquid crystal composition with ultraviolet rays via the slitsof the light blocking metal wire; and a disconnection inspecting processof inspecting whether or not a disconnection detection metal wireconducts, and if not conducting, the liquid crystal display device istreated as an inspection-rejected article.

In the liquid crystal display device manufacturing method according toanother aspect of the present invention, the metal wire forming processfurther includes forming the disconnection detection metal wire which isformed so as to surround the outside of the three sides at the outsideof the light blocking metal wire and is used to detect disconnection,and a gate wire of a circuit of the pixel region may be formed at thesame time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a liquid crystal display deviceaccording to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view schematically illustrating astructure of the liquid crystal module shown in FIG. 1.

FIG. 3 is a diagram schematically illustrating the TFT substrate shownin FIG. 2 in a field of view in the perpendicular direction to thedisplay surface.

FIG. 4 is a enlarged view schematically illustrating a portion shown inIV of FIG. 3 in relation to the wiring shapes of the light blockingmetal wire and the disconnection detection metal wire.

FIG. 5 is a table illustrating an aperture ratio in a case where theslit width S of the light blocking metal wire shown in FIG. 4 and theline width L of the metal line formed between the adjacent slits aredefined.

FIG. 6 is a diagram schematically illustrating a modified example of theshapes of the light blocking metal wire and the disconnection detectionmetal wire in the same field of view as in FIG. 4.

FIG. 7 is a flowchart illustrating a liquid crystal panel manufacturingprocess which is a process in the manufacturing method of the liquidcrystal display device.

FIG. 8 is a flowchart illustrating details of the TFT substratemanufacturing process shown in FIG. 7.

FIG. 9 is a flowchart illustrating details of the color filter substratemanufacturing process shown in FIG. 7.

FIG. 10 is a flowchart illustrating details of the substrate bonding andliquid crystal material injecting process shown in FIG. 7.

FIG. 11 is a flowchart illustrating details of the disconnectioninspecting process shown in FIG. 7.

FIG. 12 is a partial cross-sectional view schematically illustrating astructure of the liquid crystal module of the liquid crystal displaydevice in the related art.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings. In addition, in the drawings, the same orequivalent constituent elements are given the same reference numerals,and repeated description will be omitted.

FIG. 1 is a diagram illustrating a liquid crystal display device 100according to an embodiment of the present invention. As shown in FIG. 1,the liquid crystal display device 100 includes a liquid crystal module200, an upper frame 101 and a lower frame 102 which fix the liquidcrystal module 200 so as to be interposed therebetween, a circuitsubstrate (not shown) provided with circuit elements generating displayinformation, and the like.

FIG. 2 is a partial cross-sectional view schematically illustrating astructure of the liquid crystal panel 200. As shown in FIG. 2, theliquid crystal panel 200 includes a liquid crystal panel 300 which has adisplay surface 310 and controls alignment of the liquid crystal, alight guide plate 210 to which light from a light source (not shown) isincident and allows the light to travel toward the display surface 310,an optical sheet 240 which applies the light emitted from the lightguide plate 210 to a display region so as to be uniform and has aplurality of sheets, and the like.

In addition, the liquid crystal panel 300 includes an upper polarizer301 which transmits only light polarized in one direction therethrough,a lower polarizer 305 which transmits only light polarized in adirection perpendicular to the one direction therethrough, a colorfilter substrate 302 which has color filters R (red), G (green) and B(blue) for the respective pixels, a TFT (Thin Film Transistor) substrate320 which is provided with circuits (not shown) generating an electricfield for each pixel, liquid crystal composition 303 which is sealedbetween the color filter substrate 302 and the TFT substrate 320, ablack matrix 306 which is formed on the color filter substrate 302, anda seal 307 which is formed from a UV (ultra violet) curable material forsealing the liquid crystal composition 303 between the color filtersubstrate 302 and the TFT substrate 320. In addition, in FIG. 2, a lightblocking metal wire 323 and a disconnection detection metal wire 324described later are also shown as a part of the TFT substrate 320.

FIG. 3 is a diagram schematically illustrating the TFT substrate 320shown in FIG. 2 in a field of view in the perpendicular direction to thedisplay surface 310. As shown in FIG. 3, the TFT substrate 320 includesa pixel region 321 which is a rectangular region provided with pixelsformed in a matrix, a frame region 322 which is outside the pixel region321 and frames the pixel region 321, the light blocking metal wire 323which is formed so as to surround the outside of at least three sides ofthe rectangular pixel region 321, the disconnection detection metal wire324 for detecting disconnection thereof outside the light blocking metalwire 323, a driver circuit section 325 which is provided with drivercircuits for driving pixel circuits of the pixel region 321, a terminalsection 326 which mainly sends and receives information such as imageinformation to and from the driver circuit section 325 and an externalsubstrate, two terminals 327 which are included in the terminal section326 and are connected to the disconnection detection metal wire 324, andcommon electrodes 328 which are connected to the light blocking metalwire 323 and are maintained at the same potential as a common potential.

The disconnection detection metal wire 324 is connected to the terminals327 and is thus used to detect disconnection by checking conductionusing the terminals 327, for example, in a manufacturing process afterthe liquid crystal panel 300 is assembled. In a case where disconnectionis detected, cracks in the TFT substrate 320 are also regarded as havinginfluence on the pixel region, and the liquid crystal panel is treatedas an inspection-rejected article. In addition, the light blocking metalwire 323 is connected to the common electrodes 328 such that anunnecessary electric field is not generated.

FIG. 4 is a enlarged view schematically illustrating a portion shown inIV of FIG. 3 in relation to the wiring shapes of the light blockingmetal wire 323 and the disconnection detection metal wire 324. As shownin FIG. 4, the light blocking metal wire 323 has slits 340 which arelinearly formed in the wire direction such that UV rays which areapplied to cure the seal 307 shown in FIG. 2 are effectively applied,and a metal portion for blocking light in order to weaken intensity oflight from the backlight. In addition, the disconnection detection metalwire 324 is formed along the light blocking metal wire 323 outside ofthe light blocking metal wire 323. Further, in FIG. 4, the number of theslits 340 of the light blocking metal wire 323 is five, but may belarger than or smaller than that.

FIG. 5 is a table illustrating an aperture ratio in a case where theslit width S of the light blocking metal wire 323 shown in FIG. 4 andthe line width L of the metal line formed between the adjacent slits 340are defined. In addition, here, a case where the slit width S is fixedto 5 μm is shown. In addition, in the table, the aperture ratio 41.7%when the line width L is 7 μm and the slit width S is 5 μm is the sameaperture ratio as in the lower polarizer 305. In addition, thedisconnection detection metal wire 324 is fixed to 10 μm. In any case ofemploying the aperture ratios shown in the table, the seal 307 can becured by the UV rays in a state of blocking light from the backlight.

FIG. 6 is a diagram schematically illustrating a light blocking metalwire 423 and a disconnection detection metal wire 424 according to amodified example of the wiring shapes of the light blocking metal wire323 and the disconnection detection metal wire 324 in the same field ofview as in FIG. 4. As shown in FIG. 6, in the modified example, slits440 formed in the light blocking metal wire 423 are formed so as to bedispersed in a checkered pattern. In this case as well, the seal 307 canbe cured by the UV rays in a state of blocking light from the backlight.

FIG. 7 is a flowchart illustrating a liquid crystal panel manufacturingprocess which is a process in the manufacturing method of the liquidcrystal display device 100. As shown in this flowchart, the liquidcrystal panel manufacturing processes sequentially include a TFTsubstrate manufacturing process S100 for manufacturing the TFT substrate320, a color filter substrate manufacturing process S200 formanufacturing the color filter substrate 302, substrates bonding andliquid crystal material injecting process S300 for bonding the TFTsubstrate 320 and the color filter substrate 302 together and injectinga liquid crystal material therebetween, and a disconnection inspectingprocess S400 for detecting disconnection of circuits of the TFTsubstrate 320.

FIG. 8 is a flowchart illustrating details of the TFT substratemanufacturing process S100 shown in FIG. 7. As shown in this flowchart,in the TFT substrate manufacturing process S100, first, in step S101,semiconductor circuits in the pixel region 321 are formed along with thelight blocking metal wire 323 and the disconnection detection metal wire324 through a photolithography process. Next, in step S102, an alignmentlayer for aligning liquid crystal in one direction on the liquid crystalsurface side is formed. Here, although, in the present embodiment, thelight blocking metal wire 323 and the disconnection detection metal wire324 are formed along with the gate wires of the circuits in the pixelregion 321, they may be formed along with other metal wires of thecircuits in the pixel region 321. With such simultaneous formation, thelight blocking metal wire 323 and the disconnection detection metal wire324 can be formed without increasing the number of processes.

FIG. 9 is a flowchart illustrating details of the color filter substratemanufacturing process S200 shown in FIG. 7. As shown in this flowchart,in the color filter substrate manufacturing process S200, first, in stepS201, the black matrices 306 are formed on the periphery of the pixelregion 321 and the periphery of each pixel so as to prevent light fromleaking. Next, in step S202, color filters of R (red), G (green), and B(blue) are formed in the ranges of the pixels formed by the blackmatrices 306. Finally, in step S203, an alignment layer for aligning theliquid crystal in one direction on the liquid crystal surface side isformed.

FIG. 10 is a flowchart illustrating details of the substrate bonding andliquid crystal material injection process S300 shown in FIG. 7. As shownin this flowchart, in the substrate bonding and liquid crystal materialinjecting process S300, first, in step S301, a seal material is coatedon the periphery of the pixel region 321 then the TFT substrate 320 andthe color filter substrate 302 are bonded each other. Next, in stepS302, the coated seal material is irradiated with the UV rays via thelight blocking metal wire 323 to be cured. Next, in step S303, a liquidcrystal material is injected into the substrates bonded to each otherand is sealed. Finally, in step S304, the upper polarizer 301 isattached to the color filter substrate 302 and the lower polarizer 305is attached to the TFT substrate 320.

FIG. 11 is a flowchart illustrating details of the disconnectioninspecting process S400 shown in FIG. 7. As shown in this flowchart, inthe disconnection inspecting process S400, first, in step S401, it ischecked whether the two terminals 327, which are connected to thedisconnection detection metal wire 324, electrically conducts or not.Here, if they electrically conducts, inspection is passed (step S402),and if they do not electrically conduct, inspection is not passed (stepS403). With respect to the light blocking metal wire 323 formed in theframe region, the disconnection detection metal wire 324 is formed atthe outermost part. In other words, the disconnection detection metalwire 324 is formed at the outermost circumference among wires formed onthe TFT substrate 320. Through the detection of conduction in thedisconnection detection metal wire 324, it is possible to detectpresence or absence of defects of the TFT substrate 320. If there arecracks on the TFT substrate, the disconnection detection metal wire 324is disconnected and thus the two terminals 327 cannot electricallyconduct. If the disconnection detection metal wire 324 is disposed atthe outermost circumference, early detection of small cracks extendingfrom the glass substrate edge to the inside is possible.

As described above, according to the liquid crystal display device 100according to the present embodiment, even if the polarizers are small,the frame region 322 having the slits 340 has a sufficient lightblocking property via the light blocking metal wire 323, and, in themanufacturing process, the seal 307 sealing a liquid crystal materialcan be cured by transmitting the UV rays therethrough. In addition, itis possible to detect cracks of the TFT substrate 320, for example, in aprocess after the liquid crystal panel 300 is manufactured, using thedisconnection detection metal wire 324 which is formed along the lightblocking metal wire 323 and is located in the same layer as the lightblocking metal wire 323.

Although the light blocking metal wire has slits having the shapes asshown in FIGS. 4 and 6, a shape thereof is not limited to these shapes.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaim cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A display device comprising: a first substratehaving a display region and a peripheral region; and a second substrate,wherein the display region has four sides, wherein the peripheral regionincludes: a first metal wire that is formed along at least two of thefour sides of the display region; and a second metal wire that is formedalong at least three of the four sides of the display region and isdisposed at the outside of the display region and the first metal wire,wherein the first metal wire is disposed between the display region andthe second metal wire, and wherein the first metal wire has at least oneslit at an area overlapping with an adhesive.
 2. The display deviceaccording to claim 1, wherein the at least one slit is formed by aplurality of lines branching from the first metal wire.
 3. The displaydevice according to claim 2, wherein a width of each of the linesbranching from the first metal wire is larger than a width of the atleast one slit.
 4. The display device according to claim 1, wherein theat least one slit is formed in a checkered pattern.
 5. The displaydevice according to claim 1, wherein the first metal wire is maintainedat a common potential.
 6. The display device according to claim 1,wherein a width of the second metal wire is larger than a width of theat least one slit.
 7. The display device according to claim 1, whereinthe first metal wire includes material having light blocking property.8. The display device according to claim 1, wherein the first substrateis a thin film transistor substrate.
 9. The display device according toclaim 1, wherein the first metal wire and the second metal wire areformed of an identical material to constitute at least a part of onelayer.
 10. The display device according to claim 1, wherein the secondsubstrate further comprises a color filter.
 11. The display deviceaccording to claim 1, wherein the second metal wire is formed along thefour sides of the display region.
 12. The display device according toclaim 1, further comprising two terminals in the peripheral region, thetwo terminals being connected to the second metal wire at both ends,respectively.
 13. The display device according to claim 1, wherein thesecond substrate further comprises a light shielding layer whichprevents light from leaking over the adhesive, the light shielding layerbeing wider than the adhesive, and wherein the first metal wire and thesecond metal wire are provided in an area which is wider than theadhesive.
 14. The display device according to claim 1, furthercomprising: a polarizer that transmits only light polarized in aspecific direction, the polarizer being as large as the display region.15. The display device according to claim 1, further comprising apolarizer that transmits only light polarized in a specific direction,wherein the first substrate further comprises a terminal section forelectrical connection with an external substrate, having a portion ofthe adhesive provided thereon next to the terminal section, wherein thepolarizer is positioned over the display region without overlapping withthe portion of the adhesive next to the terminal section.